Multi-planar variable geometry zigzag cut articulating drilling system

ABSTRACT

An articulating drill system is provided that includes a hand-held portion and a drill portion. At least two actuators are provided for controlling at least two axes of the drill portion. A navigation system is provided to control the at least two actuators. In some embodiments, a tool is provided with the drill portion and adapted to interact with patient tissue. The drill portion can be modified to include at least two rigid objects in communication with the actuators and attached to the drill portion. The system can be used to make any linear cut within a deviation of ±1.0 mm and ±1.0°, or better in patient tissue.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/512,180 filed 17 Mar. 2017; now US Patent ______ B1 that in turn is aU.S. National Phase Application of Ser. No. PCT/US2015/051713 filed 23Sep. 2015 that in turn claims priority benefit of U.S. ProvisionalApplication Ser. No. 62/054,009 filed 23 Sep. 2014; the contents ofwhich are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates generally to computer-aided drill systems,and more specifically to a new and useful system for assisting withsurgical procedures.

BACKGROUND

In thoracic surgery, the chest cavity often must be opened and the ribsretracted. Typically, oscillating saws are used to create an arcuate cutthrough the sternum, since it is difficult to properly close andreinforce a linear sternal cut for optimal cut planes consolidation,owing in part to the lack of a definitive reference or anchoringmultiplanar structure to aid in sealing the closure. Cutting an arcuateline, however, is practically difficult and inexact with existingdevices. Ideally, the sternum should be cut in a pattern where the twohalves of the divided sternum can reunite in a manner that maximizesstability and surface area contact for primary osseous healing withmaximal available osseous points and elements.

Freehand cutting saws or drills may be operated to cut such patternslike a triangle continuous wave that is commonly and synonymouslyreferred to herein as “zig-zag” pattern. However, such free formincision patterns are inexact, prone to miss-cuts and suffer fromvibrational deviations. Other non-articulating systems exist withtracking mechanisms that display the position and orientation of thedevice on a monitor. This however requires the operator to constantlycheck a monitor during cutting and there is little assistance providedto prevent either a miscut, inadequate cut placement, or the ability toconstrain movement according to a planned and/or pre-programmed cuttingpattern.

Thus, there exists a need for a method and device that assists theoperator in precisely cutting the sternum in a pattern, whereuponclosure, the two halves are joined to provide superior stability andincreased contact surface area to promote optimal bone healing. Therefurther exists a need for a system which prevents a drill operator fromdeviating from a pre-indicated planned cutting path. There also exists aneed for a drilling system that allows an operator to compensate for acutting surface's movement while maintaining a precise cutting patternthrough a subject's sternum.

SUMMARY OF THE INVENTION

An articulating drill system is provided that includes a hand-heldportion and a drill portion. At least two actuators are provided forcontrolling at least two axes of the drill portion. A navigation systemis provided to control the actuators. In some embodiments, a tool isprovided with the drill portion and adapted to interact with patienttissue. The tool in some embodiments, can accurately mark specific areason tissue for digitization and/or registration. A drill guard isprovided in some embodiments to travel on the underside of a cuttingsurface preventing the drill from cutting any surfaces, includingpatient tissue, underneath the drill guard.

The navigation system in some embodiments provides real-time feedback toone of a position, orientation, or velocity of said drill portion. Thereal-time feedback can include information relating a surface to thedrill portion as the device is being operated to be used by a controllerto adjust the at least two actuators to compensate for surface movementor user's movement of the hand-held portion or prevent the operation ofthe device outside a pre-indicated pattern. In some embodiments, auser-feedback mechanism is provided, such as a trigger or a foot pedal.The user-feedback mechanism can be activated by a user to communicate tothe navigation system and drill that a new fixed plane of motion isdesired. In some embodiments, the hand-held portion includes an adapterfor attaching a rigid reference guide that provides the user with avisual relationship between the plane of the reference guide relative tothe plane of the drill portion.

The drill portion can be modified to include at least two rigid objectsin communication with the actuators and attached to the drill portion.

The system can be used to make any linear cut within a deviation of ±1.0mm and ±1.0°, or better in patient tissue.

In some embodiments, the linear cut cuts the sternum for thoracicsurgery in a “triangle wave pattern”.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further detailed with respect to the followingdrawings. These figures are not intended to limit the scope of thepresent invention but rather illustrate certain attributes thereof.

FIG. 1 are various exemplary triangle wave cut patterns produced by thepresent invention;

FIG. 2 is an isometric view of an articulating hand-held drill;

FIG. 3 is a more detailed depiction of the articulating hand-held drill;

FIG. 4 illustrates the drill portion articulating in two-degrees offreedom;

FIG. 5 depicts one proposed connection between the actuators and drillportion of the articulating hand-held drill;

FIG. 6 is an exemplary cutting multiplanar path that can be createdusing the inventive system;

FIG. 7 depicts a preferred configuration of the hand-held drill system;

FIG. 8 is a schematic of the external hardware and controls for thehand-held drill system;

FIG. 9 depicts the articulating hand-held drill with attachablereference guides;

FIG. 10 is a detailed view of a linear rail bearing mechanism of thehand-held drill system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention disclosed herein describes an articulating hand-helddrill system for precise cutting along any plane, but more particularlyto create a precise and smooth pattern incision along a surface ingeneral and in particular to a subject's sternum.

It is to be understood that in instances where a range of values areprovided that the range is intended to encompass not only the end pointvalues of the range but also intermediate values of the range asexplicitly being included within the range and varying by the lastsignificant figure of the range. By way of example, a recited range from1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

As used herein, a “triangle wave pattern” is defined to include at leastone half of a period, of a triangle wave, saw tooth pattern, andvariants thereof in which line segments of the patterns are arcuatebetween extrema. “Zigzag” is used herein synonymously with “trianglewave” with respect to incision patterns according to the presentinvention. Exemplary incision patterns according to the presentinvention are shown in FIG. 1 and FIG. 6 but are not meant to belimiting.

The invention described herein also represents a system whicharticulates to keep the drill in a fixed plane of motion during a cutthrough a surface after the cutting is started. It is appreciated thatthe fixed plane is maintained within a range of rotation of ±1° andtranslation of ±1 mm.

The invention disclosed herein further includes the usage of anavigation system comprised of trackable markers mounted on the deviceitself, the cutting target, otherwise providing a fixed reference framein the incision field, or a combination of such marker positions. Theusage and positioning of markers depends on factors that include: thedegree of cutting target expected movement, the accuracy requirementsfor the cut, interfacing with the surgical navigation system,radiological subject's specific data sets, and the design andergonomical features of the device.

One specific advantage of the present system is that the operator isable at any time to indicate to the system that the plane of cuttingshould change (i.e. from zig to zag).

The following description of the preferred embodiments of the inventionis not intended to limit the invention to these preferred embodiments,but rather to enable any person skilled in the art to make and use thisinvention.

An inventive articulating hand-held drill system 101 is shown generallyin FIG. 2. The main components of which include a handle 105, a drill102, and drill bit/blade 103. With reference to FIG. 3, the handlecomprises at least two rods 106 connected to the drill 102. Henceforth,the rods 106 refer to a rigid component that can be linearly actuatedand are attached to the drill portion 102. The rods are linearlyactuated by components within the handle 105, to translate and/or rotatethe drill 102 in at least 2 degrees of freedom as seen in FIG. 4. Therods controlled by components within the handle 106 maintain the drillbit/blade 103 in a desired plane independent of the orientation of thehandle 105. For example, the drill 102 can articulate, either rotateand/or translate represented as α and ‘d’ in FIG. 4, based on the amountthe rods 106 have been actuated with respect to each other. Thereforeduring a surgical procedure, the desired cut plane can be maintainedindependent of how the user's hand moves, within limits, after thecutting has started. The system 101 of the present invention may haveseveral applications for cutting any surface or any object where alinear cut or set of cuts are needed. In at least one embodiment thesystem of the present invention is optimized for cutting the sternum,but is not limited to that use. Other surgical contextual locations thatare cut by the inventive system illustratively include a knee joint, hipjoint, spine, shoulder joint, elbow joint, ankle joint, jaw, tumor site,joints of the hand or foot, and other appropriate surgical sites or forany osseous cut planes in the same fashion and logistics. Those skilledin the art will appreciate the devices use in a variety of differentsurgical applications such trauma, orthopedic, neurology, ENT, oncologyand the like. Additionally, the system can be used to assist a user inperforming surgical operations that require a linear or set of cuts suchas but not limited to total hip arthroplasty, total knee arthroplasty,bone osteotomies, spinal surgery, microsurgical scalpel stabilization,plastic surgery, cranial surgeries, and craniofacial. Similarly, itshould be appreciated that although the disclosed invention is describedfor use in a medical setting, other applications for the device can beused wherever an accurate planar cut needs to be achieved and/orplanned, such as for making cuts for construction, welding/laser cuttingstability, aircraft inspection, bonding compound (e.g. BONDO®)smoothing, carpentry, masonry, soldering, sewing applications, or forcreating precise rivet patterns on large work pieces.

Drill

The inventive system 101 provides a mechanism for cutting the intendedcutting surface. The construction and types of drill and various cuttingbits/blades for cutting the sternum or other osseous tissue are wellknown in the art. For example, it is known in the art that drill forhuman tissue and drills for wood, while similar, are distinctlydifferent because of their intended use and differences in sterilerequirements. The drill is alternatively a saw, or any other operablecutting device presently known in the art. Commercially availablesurgical saws include the cardiothoracic DBC and DPX series manufacturedby deSoutter Medical, as well as oscillating tip saws used in total hipand knee arthroplasty such as the System 7 Precision Saw manufactured byStryker. Other types of cutting bits/blades may include burrs, endmills, reamers, cutters, engraving tools, drill extensions, broaches,routers, sanders, and any other tool attachable to a reciprocating orrotary drill/saw 102.

The drill in certain inventive embodiments has a handle 105 configuredfor holding by a human hand, in addition to one or more adjustmentsincluding blade adjustments, handle adjustments, or knob adjustments(not shown) in order to position the drill, its handles, or knobs,particularly to the preference of a user. In at least one embodiment,the drill is hand-held by the operator as a standalone unit with noexternal constraints capable of receiving and executing actuationcommands wirelessly. In other embodiments, the drill and/or itscomponents are electrically connected to external units 108 such as butnot limited to computers, processors, controllers, power supplies,navigation system and/or combinations thereof.

In one embodiment of the device, the rods 106 are attached to the drill102 by means of a hinge mechanism 107 that allows the drill to move inat least two degrees of freedom. In other embodiments, the rods areattached to the drill by means of a captured sphere 112 where one of therods is fitted into a sleeve 113 that allows the sphere to slide backand forth as seen in FIG. 5. This allows for optimal movement of thedrill as the rods are actuated linearly.

In certain inventive embodiments, the system 101 includes a drill guard.The drill guard 110, when present, travels on the underside of a cuttingsurface and inhibits the drill bit/blade 103 from cutting any surfacesthereunder. In a surgical context, the drill guard 110 prevents theinadvertent cutting of soft tissue beneath the cutting surface. Drillguards are currently present on surgical saws and come in differentconfigurations. For example, a craniotomy saw has a drill guard havingof an angled footed attachment seated below the blade to prevent thedamaging of brain tissue when cutting the skull. In one certainembodiment the drill guard 110 is formed of a sphere within a sphereattached to the tip of the drill bit/saw blade 103 that rides along theunderside of the sternum while not spinning significantly with the drillrotation to avoid possible friction burns and cutting of soft tissue.

Articulating Drill

The actuation of the rods 106 provide the controlled movement to thedrill bit/blade to be fixed along the desired or pre-planned planes. Inat least one embodiment, two rods 106 are actuated independently toallow the drill bit/blade 103 to be operated in at least two degrees offreedom. As shown in FIG. 4, if the two rods are actuated in opposingdirections the drill rotates, for example, an angle α. If the two rodsare actuated in the same direction the drill translates, for example, adistance ‘d’. The actuation occurs in real-time adjusting the rodsappropriately to maintain the desired cut-plane during cutting. Thedegree and amount of rotation, α, and/or translation, ‘d’, depends onthe desired cut plane relative to the orientation and position of thehandle during cutting. In another embodiment, the drill includes ofthree or more rods 106 attached to the drill 102 actuated to allow thedrill bit/blade to be operated in three degrees of freedom or more.Similarly, the amount each independent rod is actuated controls thedesired cut-plane.

The mechanisms for controlling the rods can be achieved by a pluralityof components assembled within the handle 105. This can include but notlimited to synchronous motors, servo motors, actuator motors, wormdrives, gears, screws, bearings, power supply, hydraulic systems,pneumatics systems and/or combinations thereof. The mechanism foractuating the rods 106 can be created by any linear actuator. Thecomponents housed within the handle 105 can are orchestrated to controlthe position and orientation of the drill 102 using signals fromcontroller/s 108 including a microprocessor that may be housed withinthe device, attached to the device, and/or located externally. In oneembodiment, the rods are actuated by two independent linear actuators bytwo separate controllers 108 receiving signals from a real-timeprocessor 109. A real-time computer 109 provides feedback tocontroller/s 108 and/or actuating components to maintain the correctplane of the drill bit/blade during cutting based on the position andorientation of the drill portion sensed from the optical tracking system118. The actuators that maintain the desired plane may also be in directcommunication with the navigation system, an operator feedback system, acomputer, processor/s and/or combinations thereof.

In a preferred embodiment, the navigation system tracks the position andorientation of the drill portion 102, independent of the handle. Atracking array 111 including active or passive tracking markers 104, isattached to the drill 102. There are specific control advantages totracking the drill 102 as opposed to the handle portion 105. Oneadvantage is there is no need to calibrate the drill 102 relative to thehandle 105 because the drill 102 is the moving portion and is beingdirectly controlled from the rigid handle 105. In other embodiments atleast three or more active or passive markers are directly attached toand/or incorporated with and/or within the drill portion 102 to trackthe drill independent of the handle. In another embodiment the threeactive markers are configured on a marker array 111 that can be attachedto or incorporated with the drill portion 102. The active or passivemarkers can be arranged on the drill 102 in a plurality ofconfigurations and numbers.

In other embodiments the handle 105 may be tracked by the navigationsystem or the entire position and orientation of the drill is tracked.In a further embodiment the handle and drill may include independentsets of active and/or passive markers so the two components are trackedrelative to one another by one or more navigation system/s.

A more detailed view of the preferred embodiments of the inventivehand-held drill system is shown in FIG. 7. As previously described, thehand-held drill system includes a drill bit/blade 103, and a drill 102for linearly reciprocating or rotating the drill/bit blade 103. Acarriage 201 connects the drill portion with two actuating rods 207. Thetwo rods 207 shown here are linear rails that can slide along a linearguide 221. At the proximal end of the linear rails 207, are screw nuts209 attached thereto. The screw nuts are in communication with leadscrews 211. Servo-motors 213 rotate the lead screws 211 thereby causingthe screw nuts 209 to translate along the lead screw axis. The linearrails 207 attached to the screw nuts 209 therefore translateaccordingly. Thus, the controllers can control the servo motors torotate the lead screws 211 to obtain a final position and orientationfor the drill portion as previously described.

The two servo motors 213 are encased in a housing 217 for stability. Thehand-held drill system in FIG. 7 also includes two electrical inputports 205 and 219. The electrical input port 205 is adapted to receivepower and/or motor control inputs for the drill 102. The electricalinput 219 is adapted to receive power and/or motor control inputs forthe two servo motors 213. In addition, the carriage includes a fixationmechanism 203 to attach or fix a tracking array to the drill portion.Finally, a trigger 215 is incorporated with the hand-held portion toprovide a mechanism for user input.

A preferred embodiment of the external hardware and controls for of thehand-held drill system is shown in FIG. 8. A real-time computer 301 isprogrammed to provide a majority of the computational tasks for thesystem. Data from the optical tracking system 303 is sent to thereal-time computer 301 which may calculate the pose of any trackedobjects in the operating room. Alternatively, the optical trackingsystem 303 may compute the pose of the tracked objects and send theposition data directly to the real-time computer 301. The measured poseof the drill portion is compared to the desired or pre-planned pose inthree-dimensional (3-D) space. The comparison may be made relative toother tracked objects in the operating room, such as a bone with a fixedtracking array. The user may pre-plan a desired plane in the operatingroom using a user interface computer 305. The user interface computer305 may be used for a variety of other applications as described herein.The real-time computer 301 and user interface computer 305 maycommunicate through a wired or wireless network 307.

The real time computer 301 sends control set points to two servo-motorcontrollers, 311 and 313, to correct for any deviations between theactual measured pose of the hand-held drill portion and the desiredposition. One servo-motor controller 311 controls the rear servo-motorand the other servo-motor controller 313 controls the front servo-motor.The servo-motor controllers may be for example EPOS motor controllersmanufactured by Maxon Precision Motors, Inc. (Fall River, Mass.). Thereal-time computer 301 also processes user commands from the trigger 215and/or a foot pedal (described below) from a trigger/pedal integrationmodule 315. Commands from the real time computer 301 and thetrigger/pedal integration module are sent to a drill controller 321,which connects to the drill input port 205 to control the drill 102. Thedrill controller 321 may be for example the BienAir motor controllermanufactured by Bien-Air (Bienne Switzerland). The front servo-motorcontrol 313, rear servo-motor controller 311 and trigger/pedalintegration module 315 connect to a cable splitter 317. From the cablesplitter 317, the servo-motors 213 are controlled accordingly receivingthe instructions via electrical input port 219.

Navigation System

In one embodiment of the device, the position and orientation of thedrill is tracked to determine its relative location in space and to thepatient's anatomy. Many types of navigation systems are available suchas the Polaris Optical Navigation system manufactured by NDI or theaccuTrack 500 manufactured by Atracsys which utilize cameras to trackpassive and/or active markers in the surgical field. Similarly, theposition and pose of the drill can be tracked using active or passivemarkers 104 mounted upon the drill 102. The active or passive markerscapable of emitting or reflecting optical signals such as visible light,infrared, UV, radio-frequency, sound waves, magnetic fields or any othersignal capable of communicating with a navigation system. The opticaltracking system 118 of the navigation system can be electricallyconnected to a real-time processor and/or computer 109 to, in real time,track the position and orientation of the drill 102 and send controlsignals to the controller 108 that control components in the handle toaccordingly actuate the rods in the desired plane. In one embodiment,the optical tracking system can capture the position of the opticalmarkers synchronously. In other embodiments the position of individualoptical markers are captured by the optical tracking systemsequentially.

In another embodiment of the device, the navigation system alsoincorporates inertial measurement units such as accelerometers and/orgyroscopes incorporated and/or attached to the drill portion foradditional tracking information as to the velocity, position andorientation of the device (not shown). In one embodiment the data fromthe inertial measurement units can be fused with the data from theoptical tracking system in the processor/computer 109 to estimate theposition, velocity and orientation of the drill portion using filteringtechniques well known in the art, such as Kalman filtering. The inertialmeasurement units can transmit data through an electrical connection ortransmitted wirelessly using WiFi, TCP/IP, UDP, Bluetooth or LiFiconnection to a real-time processor and/or computer to receive andprocess the data. In another embodiment, GPS (not shown) can similarlybe used as a method for tracking the drill portion and can be used inassociation with the optical data from the optical tracking system andthe inertial measurement units.

In one embodiment the device is tracked using tracking units such as butnot limited to active markers, passive markers, inertial measurementunits, GPS and/or any combination thereof. Additionally, the trackingunits can come in a plurality of numbers, orientations and positions onthe drill to ensure accurate tracking. In another embodiment of theinvention, a tracking array 111 including active or passive markers 104can be electrically connected to the drill and housed at a plurality oflocations or can be directly incorporated with the drill portion 102.FIG. 3 depicts an example of the tracking array 111 on the drill portion102 in one embodiment.

The navigation system provides real-time feedback relating a drillingsurface to the position and orientation of the drill 102 duringoperation. An additional set of tracking units can be attached to theanatomy and provide an anatomical reference frame to monitor anymovement of the surface. Additionally, optical markers can be located ata fixed position in the operating room to provide an origin as acoordinate frame of reference for the optical tracking system 118. Thenavigation system can then detect the drill and anatomy position andorientation to signal any appropriate adjustments to the rods via acontroller 108 and/or the components within the handle 105 to maintainthe desired plane of cutting. The navigation system including opticaltracking, inertial measurement units and/or GPS can communicate with theactuator components housed in the handle 105 either directly or throughother devices such as a computer/processor 109, controller 108 so thedesired plane is maintained to follow a pre-planned cutting path,compensate for user error and/or anatomical movement and any combinationthereof.

In one embodiment, the optical markers 104 are LEDs that can be actuatedby a microprocessor located on the drill system 101 capable of actuatingthe LEDs to transmit data at a high rate. The microprocessor is capableof transmitting a plurality of data types. One example includes the datafrom the inertial measurement units that can improve the latency of thesystem and provide a fast tracking mechanism. The drill system 101 mayadditionally include wireless receivers attached or incorporated in thedrill portion 102 and/or the hand-held portion 105 that can receivesignals and/or data from a computer, processor, controller or thenavigation system to maintain the desired plane of cutting. Thereceivers can additionally be optical receivers connected tomicroprocessors attached to or incorporated in the hand-held portion 105and/or the drill portion 102. The drill system can also includemicro-controllers within the hand-held portion 105 and/or the drillportion 102 that receive signals by way of the receivers on the drillsystem 101 capable of controlling the actuators and can further improvethe latency of the system.

In certain inventive embodiments, the system 101 records a pre-indicatedcutting pattern or a cutting pattern is taught by an operator prior tooperation of the drill. In at least one embodiment, the real-timeprocessor 109 is taught referential points by contacting the drilland/or drill bit/blade 103 tip to operator specified target points. Thenavigation system that can include an optical tracking system 118,inertial measurement units, and/or GPS can all be used for tracking andsetting the desired points and planes specified by the user. In at leastone embodiment, the operator specified target points are recorded by oneor more computers 109, with one or more computers in communication withthe optical tracking system 118, inertial measurement units, GPS and/oran operator- feedback mechanism portion thereof. For example, in anexemplary embodiment, the cutting pattern depicted in FIG. 6 shows a“zigzag” 116 cut path on the anterior portion of the “sternum” 114, butis kept in a straight line 117 on the posterior of the sternum. In oneembodiment the user can pre-define the “zigzag” cut path by selectingthe corner points 115 of the “zigzag” to be registered and recorded bythe computer/processor 109 by way of the navigation system. The operatorwould then steadily cut a straight line down the middle of the sternum114. The device would then articulate to keep the drill tip (under thesternum) on the best fit line between the indicated corner points 115while the drill body passes through the corner points 115 on top in aline-to-line manner. The resulting pattern provides definitive anddistinct referencing landmarks and supporting structure to connect thetwo halves of the sternum post-operation.

In another embodiment, the real-time processor 109 can be connected toanother processor/computer or directly to a monitor (not shown) todisplay information regarding the procedure. The monitor displaysinformation such as, but not limited to, the position of the drillrelative to the anatomy, the progression of a procedure, proceduralsteps, accuracy of the cutting, warnings, safety zones, theintra-operative plan, a pre-operative plan, the depth of the cut, andany combinations thereof. Additionally the user can interface with themonitor by means of a mouse, keyboard, pendant, touch screen, and anycombinations thereof. The user interface allows the user to perform aplurality of tasks such as, but not limited to, defining anintra-operative plan, selecting new planes to cut, halt or abort aprocedure, change the cutting speed, define cutting planes, placingthree dimensional (3-D) virtual implants relative to the anatomy basedon cuts that have been performed or want to be performed. In onespecific embodiment, a 3-D model of the anatomy is shown on the displayand update as parts of the actual anatomy is removed by the drill. Theuser may then virtually display how the implant may fit on the modifiedbone before making any proceeding bone alterations. This may be used asa form of real-time intra-operative adjustments during a procedure toaccurately fit an implant on the bone. Additionally, the user interfaceallows the user to send information to the processor/computer 109, thecontroller/s 108, the optical tracking system 118, the drill system 101,the drill portion 102, other external components and any combinationthereof.

Operator Feedback Mechanism

The operating feedback mechanism allows for quick communication from anoperator to interact with the inventive system 101. The operatingfeedback mechanism may alternatively be a system of one or moremechanisms, buttons, switches, and may include one or more computers forinterpreting the operator's interaction. In certain inventiveembodiments, an operator-feedback mechanism is provided for enabling anoperator to communicate with the system for various reasons. In certaininventive embodiments, the operator-feedback mechanism is a trigger or afoot pedal. In certain inventive embodiments, the operator-feedbackmechanism can be activated by an operator at any time to communicate tothe navigation system and device that the plane of cutting should changefrom one plane to another such as from zig to zag. The change from oneplane to another will match an indication given by user that relates theway the user is holding the device at the time, i.e. the plane thatmatches the vector through the handle of the device, or the plane thattargets a pre-indicated endpoint on another part of the sternum that wasindicated before the cutting.

The operator feedback mechanism provides one method to indicate a changein the desired cutting plane. In another embodiment, the real-timeprocessor 109 and optical tracking system 118 can automaticallydetermine from the pre-defined points/planes indicated by the user thatthe change of the plane has occurred. The optical tracking system knowsthe location of the anatomy relative to the drill portion and has beentaught an intra-operative plan by the user. As the user is cutting andgets to a pre-defined point where the plane is to change, the user cansimply change the orientation of the drill portion to the new plane andthe real-time processor 109 by way of the optical tracking system 118can automatically know that the plane has changed and maintain the newplane. Therefore the user wouldn't necessarily need an additionaltrigger or foot pedal to indicate the plane has changed. In oneembodiment, the user can have both the option to have the computerautomatically update the new plane, or have the option with a trigger orfoot pedal to indicate to the system of a new plane.

In another embodiment, a trigger (not shown) is incorporated to thedrill system 101 and can be used by the operator to control the speed ofthe drill. The amount the trigger is de-pressed can correlate to anincrease in the speed of the drill bit/blade 103. The amount the triggeris pulled may have a linear or non-linear relationship as to the speedof the drill bit/blade. The trigger can be located on the hand-heldportion 105, or to the drill portion 102. The speed trigger can be indirect communication with the drill portion 102 to control the speed.

Articulation Mechanism

The manufacturing tolerances and assembly of the components can have asignificant effect on the accuracy and performance of the articulatingdrill. In one embodiment, with reference to FIG. 10, the articulation ofthe drill portion 102 is created by actuator motors rotating a leadscrew 123. A lead screw nut 122 is connected to a compartment 124 thatconnects to a linear assembly 125. Therefore the lead screw nut 122 isconnected to the linear assembly by way of compartment 124 and notdirectly to the linear assembly 125. Within compartment 124 is amechanism with a precision spherical component 121 located within aprecision fit bore. The mechanism allows for motion in the Z and X axisand rotation around the lead screw and all axes but constrains themotion in the Y direction therefore enabling the transmission of linearmotion to articulate the drill-portion appropriately. The purpose of themechanism is to remove the possible situation of an over constraint leadscrew and linear rail assembly due to variation in manufacturing andassembly tolerances.

Reference Guides

During certain medical procedures, such as total knee arthroplasty,multiple planar cuts need to be made to prepare the tibia and femur forthe implant. As the drill bit/blade is driven deeper into the bone, theuser has less visibility as to the cut at the tip of the blade. Withdeeper cuts it becomes more difficult to control the plane in the deeperregions. Therefore a plurality of different attachments can be assembledto the hand-held portion 105 and configured to provide the user with areference guide with respect to the position and orientation of thedrill bit/blade. Referring to FIG. 9, the hand-held portion 105 mayinclude an adapter 119 wherein different types of reference guides 120are attached to help guide the user. The reference guides provide theuser with a visual continuous confirmation process as to the desiredplane of the drill bit/blade with respect to the handle. Therefore theuser may use the referencing guides to hold the handle in an orientationand position that will aid in maintaining the drill bit/blade in thedesired plane. This can be especially useful with deeper cuts where itmay be difficult to control the cutting plane. This can also minimizedeeper cuts variable trajectory changes from pre-planned optimal cuttingplane trajectory.

In one embodiment the referencing guides can be simple rigid objectsconfigured as shown in FIG. 9 attached to both sides of the hand-heldportion. In this embodiment, the guides match the plane of the cuttingplane but can also protect soft tissues as a user cuts the planelaterally and/or provide a reference as to how deep the drill bit/blade103 plunges into the bone. The guides may be rigid but pliable tominimize risk to any soft tissue the reference guides may encounter. Theguides aid the user by providing a physical referencing plane directlyin sight of the surgical site and/or surgical line of sight attached tothe hand-held portion relative to the working portion 102.

In another embodiment, the reference guides are provided by a plane offluid that is propelled in the desired plane. The plane of fluid mayalso be used to irrigate, control the temperature gradient duringcutting, and/or bone chip removal in the surgical site. In oneembodiment, fluid conduits can be attached to one and/or both sides ofthe hand-held portion by way of the adapter 119. The fluid can berouted, or fluid conduits can be assembled, to spray the fluid in aplane that provides the similar visual reference guide as to the desiredplane of cutting with the plane of the drill portion with respect to theposition and orientation of the hand-held portion. In one embodiment,the plane of fluid can be sprayed in a fan-shape. In another embodiment,the fluid can be sprayed in a straight stream. In other embodiments, oneor more streams of fluid are used to provide the visual reference guidein a fan-shape stream/s, straight stream/s and/or combinations thereof.The stream of fluid can be configured to spray from a position above,below, on the side, and/or both sides of the drill bit/blade but aimedto provide the user with a reference between the desired plane ofcutting with respect to the position and orientation of the hand-heldportion. The fluid may be for example saline, saline with antibiotics,or a fluid with compound/s that would be of benefit to the patient as acertified surgeon would deem appropriate. Additionally, the stream offluid or a clear plastic reference guide can be illuminated by an LED toprovide the user with better visual feedback as to the desired cuttingplane.

In other embodiments, a nozzle attached to the end of the fluid conduitscan be used to adjust the flow and/or shape of the fluid. For example,the nozzle can be rotated to change the shape of the plane of fluid froma fan-shape to a straight stream. Such nozzles are well known in theart. Similarly, the user can have control by way of a user-feedbackmechanism as to whether the fluid is on, off and/or change the velocityof the fluid being propelled into the surgical site.

In another embodiment, the irrigation tubing is replaced by a canisteror pressurized compartment that can be attached to the hand-held portionas a stand-alone unit. For example, a container including a fluidcompartment and pressurizing compartment in communication that canpropel the fluid by means of manual pressurization or from a CO₂canister therefore removing the necessity to have an external pump orbulky irrigation tubes attached to the hand-held device. Therefore thedevice can still be a wireless standalone unit with no externalconnections to maintain ease of use of the device for the user.

Device Feedback

The use of tactile/haptic, audio and visual feedback for the hand-helddrill system can provide the user with additional cues and informationfor performing a surgery. In one embodiment, the hand-held portion 105may contain additional actuators, gyroscopes, inertial measurementunits, vibrotactile devices that can provide kinematic feedback to theuser. There are systems in the art that provide the sensation of forceacting on the hand when the device is moving in a particular direction.One such example is the GyroTab being developed by Microsoft Research,which is a hand-held device that provides reactive torque feedback. Whenthe device is translated or rotated in a particular direction, thedevice provides an opposing reacting force. The hand-held portion 105may contain similar elements to help guide the user during the procedurefor additional stability and/or to aid in finding pre-operative plannedplanes. The haptic feedback may also be used to guide a user to a safetyzone where the drill portion 102 can be engaged as a safety feature ofthe device.

Tactile feedback can also provide the user with feedback to adjust thehand-held portion to the desired cutting plane by way of a mechanism incommunication with the user's hand. In one embodiment, the tactilemechanism is a trigger located on the front of the hand-held potion incommunication with a user's finger. In other embodiments, the trigger islocated on the back of the hand-held portion in communication with auser's thumb. The trigger can rotate and translate a user's fingerindicating the amount of error between the hand-held portion and thecutting plane of the drill portion. If the hand-held portion is orientedor positioned an angle or distance from the desired cutting plane, thetrigger will provide the user with feedback to adjust the hand-heldportion by rotating and/or translating in the direction the hand-heldportion needs to be adjusted to maintain the plane. In otherembodiments, the trigger can comprise a rotational portion on thetrigger that rotates to provide the user with tactile feedback to adjustthe hand-held portion accordingly to maintain the cutting plane. Thespeed, direction and/or continual rotation of the rotational portion onthe trigger can indicate the amount, direction, and/or degree thehand-held portion needs to be adjusted to maintain the cutting plane.The trigger can also translate to provide the user with tactile feedbackto adjust the hand-held portion to minimize translational error betweenthe hand-held portion and the desired cutting plane.

The tactile feedback can also be provided by a mechanism that isconnected to the drill portion and to the hand-held portion incommunication with a user's hand. In one embodiment, one end of a rigidstructure such as a bar or rod is fixed perpendicular to the drillportion. The other end of the rigid structure is perpendicularly fixedto one end of a flexible material such as Nitinol. The other end of theflexible material is fixed to the hand-held portion which is incommunication with the user's hand. The mechanism provides the user withfeedback as to the plane of the drill portion relative to the hand-heldportion. If the position and/or orientation of the hand-held portiondeviates from maintaining the desired cutting plane, the flexiblematerial will bend on the user's hand or fingers providing forcefeedback to adjust the hand-held portion in the opposing direction ofthe force. No force from the flexible material would indicate thehand-held portion is correctly aligned to maintain the drill portion inthe desired cutting plane.

In other embodiments, the tactile feedback mechanism on the hand-heldportion in communication with the user's hand can provide information asto a new plane of cutting based on a pre-operative or intra-operativeplan. For example, when the user reaches a target point to change theplane of cutting, the trigger, capable of providing translational androtational feedback, can indicate to the user the position andorientation of the new plane. The trigger can be in communication withthe real-time processor to facilitate the feedback to the user by way ofmechanisms within the hand-held portion.

In another embodiment, audio feedback can be provided by the system toassist the user for a variety of different purposes. For example but notmeant to be limiting, the system may notify the user when the correctplane or plane density has been found or reached, notify the user tochange planes, warn the user if the drilling portion is outside ofcertain limits or are approaching limits the system can no longer adjustfor, etc. The sounds can be any audible signal such as a beep, variablebeeping sequence, audible voice of a certain language or dialect, orcombination of sounds that can convey the message to the user. Differentsounds can be associated with different functions. Additionally, theaudible sounds may be associated with messages or signals that areprompted on a monitor.

In one embodiment, the system includes visual feedback. In addition toor in substitution of the monitor connected the real-time processor, theuser may wear a pair of glasses. The glasses with embedded elements orexternal elements capable of displaying a plurality of visual data tothe user during a procedure. The glasses may be in electrical and/orwireless communication to receive signals from the real-time processor109, the optical tracking system 118, the drill system 101, the drillportion 102, another external device and any combinations thereof. Thetypes of data that can be viewed by the user may include but not limitedto the progress of the procedure, a previous procedural step, a currentprocedural step, a future procedural step, the accuracy of the planarcut, warnings that the device is out of working range, guidance to aparticular plane, a superimposed model of the individual anatomy, asuperimposed model of a pre-operative or intra-operative plan, etc.

Safety and Sterility

Usability and safety of using an articulating hand-held drill system iscritical in a medical setting. In one embodiment of the device, a safetycheck and/or volume is created so the drill can only be engaged when itis intended. For example, the real-time processor/computer 109 will onlysend signals to the controller 108 and actuating components within thehandle 105 when the drill portion is in an appropriate safety volumewithin a clinically safe range surrounding the plane definedintra-operatively or pre-operatively. The navigation system, utilizingpatient specific data in connection with the real-time processor candetermine if the drill portion is in the appropriate volume and/ordesired plane. In another embodiment a light or warning signal can beincorporated on the drill system 101 that turns green indicating to theuser that the drill is operable and within the safe zone, or a redsignal indicating the drill bit/blade is inoperable and outside of asafe zone. The signal may be in the form of an LED light or displayattached or incorporated onto the drill portion 102 or handle 105. Anadditional embodiment can provide audio cues that the drill portion 102is in the safe volume or non-safe portion. The audio cues can be in theform of a beep, series of beeps, a changing tempo of beeps or variablesequence of target proximity annotation, voice recording, or any otherreasonable arrangement of audio signals to indicate safe vs. non-safezones.

Any medical device has to be sterile or have a sterile barrier to reduceany risk of infection to the patient. In one embodiment, a sterilebarrier can be draped over the drill system 101 wherein the drillbit/blade 103 can be removed from the drill portion 102 to be sterilizedor disposed of In another embodiment, the entire drill portion 102 canbe detached from the hand-held portion 105 to be disposed of ordisassembled and properly sterilized. The materials of the device thatmay come into contact with the patient shall be made of biocompatiblematerials known in the art to ensure patient safety. Additionally anycomponents for re-use shall be capable of sterilization by methods wellknown in the art.

Other Applications

The hand-held drill system described herein can be utilized for otherapplications by changing the drill bit/blade with different functionalend effectors. The drill bit/blade 103 can be replaced with a tool forcreating visual markings on the bone, such as a surgical marker or pen.Considering the necessity for making precise planar cuts in differentsurgical applications the device can be used for outlining or marking aparticular plane on a bone to be cut that aids a surgeon in definingsurgical cuts, and intra-operative planning. There are many devices thatattempt to define the tibial and femoral cuts to restore the mechanicalaxis of the knee. The devices mark location where cuts should be madeand can be bulky extruding from the surgical site of the knee joint andexternally connecting to the talus to correctly mark the alignment ofthe cut. The drill system with the adapted visual marker instead of thedrill/bit blade can define cut locations very accurately based on theaccuracy of the optical tracking system with the markers attached to thedrill portion relative to the markers attached to the anatomy. In oneembodiment, the drill system with the visual marker tip can be used tocreate cross hairs as to the position and orientation of the keel of atibial implant in total knee arthroplasty. Additionally, specific tototal knee arthroplasty, after a surgeon has made the distal femoralcut, the drill system can be used to mark a line to accurately place afour in one cutting block to finish the rest of the procedure withmanual instruments.

In other embodiments of the invention, the drill bit/blade 103 can bereplaced with a tool to allow for the articulating drill system to beused for digitizing and/or registering to match a plurality of differentcoordinate frames with respect to each other. The drill system can beused to register for example but not meant to be limiting, pre-operativepatient data, such as from MRI or CT, CT/MRI fusion data,intra-operative data, such as fluoroscopy, 3D simulated models of apatient's anatomy, patient specific 3D anatomical model and general 3Dmodels of anatomy, the location and orientation of optical markersand/or trackers with respect to a patient's anatomy, to calibrate theoptical tracking system coordinate frame, to designate specific pointsin an operating room relative to a patient's anatomy and/or relative toan optical tracking system and/or relative to optical markers ortrackers, etc. One skilled in the art would appreciate the functionalityof utilizing the hand-held device for matching various coordinate framesrelative to each other within a medical setting. The registration can beachieved by changing the drill bit/blade with a rod comprising asemi-sharp tip, or small ball probe, to locate and register specificpoints on the objects that allows the real-time processor 109 to matchthe coordinate frames of the various objects with respect to each otherto allow for the accurate tracking of each of the objects during asurgical procedure.

In another embodiment, the articulating drill system can be used in acompliant mode such that the drill system can be used for methods otherthan cutting. Compliant mode may be activated for registration asdescribed above. Additionally, compliant mode may be used, inconjunction with a different tool attached to the drill portion otherthan a drill bit/blade to contour and define a surface that can bemodeled and/or stored in a computer. By placing the new tip and draggingit along a surface, the curves, undulations, contours, etc. can besensed by the tool and recorded by a processor/computer. As long as thetool tip is in contact with the surface, during the recording process,the drill portion will move with respect to how the surface moves. Themethod may be used to re-create and define the surface. The approach mayalso be used as a fast way to register irregular anatomy with thecoordinate frames of other objects within the room or with thecoordinate frame of markers/trackers attached to that particularanatomy.

Attachments

In another embodiment of the device, other attachments can be placedonto the drill system 101 that provides the user additional support tohold the handheld system. An extension to the bottom of the hand-heldportion can allow the user to use two hands to operate the articulatingdrill providing more stability and control. In another embodiment, asurgical glove that the user can wear directly interacts with thehand-held portion that provides additional stability for manipulatingthe drill system. The glove may include a locking mechanism thatsupports the hand in the desired plane of cutting that can be adjustedaccordingly when the user needs to change planes. Additionally, theglove can include guides or notches, for example, on the forefinger ofthe glove that the hand-held portion can align with to provide anadditional referencing guide as to the desired plane of cutting andoptimal hand held—user ergonomics. This is important for surgeons'safety and demanding cases.

In another embodiment, fluid conduits can be attached to the hand-heldportion by way of the adapter 119 that can propel fluid into thesurgical site but not necessarily to provide a reference plane asdescribed previously. In this embodiment, the user can propel fluid atdifferent locations in the surgical site by adjusting the hand-heldportion 105, while the navigation system and actuators maintain thedrill potion 102 in a desired cut plane. Therefore the user canirrigate, chip bone, or visually clear other locations in the surgicalsite within the limits of α and ‘d’ in FIG. 4 of the drill system 101,while the drill portion 102 maintains the desired cut path. The fluidconduits can be attached to the outer surface of the hand-held portionsuch as by way of adapter 119 and/or there can be an attachment forexternal fluid conduits to fluid conduits housed within the hand-heldportion. For example, one or more fluid conduits can be attached to oneor more ports at the bottom of the hand-held portion that provides afluid connection with conduits within the hand-held portion. Theinternal conduits are connected to an exit port or nozzle on thehand-held portion that faces the surgical site. The user may indicatewith a user feedback-mechanism like those described previously to turnthe fluid on, off, and/or control the velocity of fluid.

Two Degrees of Freedom vs. Three Degrees of Freedom

There are different advantages to having a device that operates in twodegrees of freedom and of a device that operates in three degrees offreedom in terms of surgical technique, control advantages, ergonomics,etc. For a two degree of freedom device, the kinematics are more simple,the motors used in the handle 105 can be larger, and the range of motionin the two degrees can be greater without compromising an ergonomicaldesign when compared to a three degree device. However, a three degreeof freedom device would provide a user with an additional degree ofmovement. For example, when cutting the sternum using a three degree offreedom device, the orientation of the drill can be controlled to benormal to the plane of the sternum at all times. The surgeon canindicate that the plane is to change while cutting and the device iscapable of doing so, thus the transition points will not present adiscontinuity of the drill orientation in making the planar change. Fora two degree of freedom device, however, the orientation of the nextplane can be determined as the orientation of the drill at the pointwhere the planar transition is made, since the normality of theorientation relative to the sternum is not particularly critical, aslong as it is within a clinically acceptable standardized range.

EXAMPLES

It is to be understood that while the invention has been described inconjunction with the detailed description thereof, the foregoingdescription is intended to illustrate and not limit the scope of theinvention, which is defined by the scope of the appended claims. Otheraspects, advantages, and modifications are within the scope of thefollowing claims.

Example 1

In cardiac surgery use the inventive system is used. The system includesan articulating hand-held drill tracked by a navigation system, wherethe device can articulate to keep the drill in a fixed plane of motionduring a cut through a patient's sternum, independent of how thesurgeon's hand moves, within limits, after the cutting is started. Thesurgeon uses trackable markers or reference devices mounted on thedevice itself, and on the bony anatomy on the sternum to compensate thecutting pattern for the movement of the sternum due to a patient'sbreathing in order to preserve a high accuracy and consistency cut.

The surgeon begins cutting along the first plane of the cut. The surgeonreaches the desired area where the surgeon would like to alter the cutto a zigzag pattern and indicates to the device, by pulling a triggerthat the plane of cutting should change.

A drill guard is used, located beyond the tip of the drill, riding alongthe underside of the sternum as the bone is cut, such that the drillwill not cut into soft tissue below the bony anatomy. The surgeon beginsto cut in a zig direction while the articulating maintains the movementof the drill along the same precise direction, compensating for anydeviations that may occur by the surgeon movement during the cut. Thesurgeon pulls a trigger on the drill, indicating to the navigationsystem to allow the surgeon to change directions in to the zagdirection. The navigation system communicates to the actuatingcomponents that will maintain the plane in the zag direction andpreventing the surgeon from going back in the zig direction unless, anduntil, another operator feedback mechanism is used. The surgeon repeatsthis process along the length of the sternum. Upon completion the zigzag pattern is found to make closing the sternum after cardiac surgeryhas completed, much easier to perform and stable. Additionally, by usingthe above example, the surgeon can optimize osseous consolidation andpotentially minimize sternum rewiring reoperations.

Example 2

The procedure of Example 1 is re-performed, however a pre-indicatedendpoint is used and the pattern is pre-indicated by the surgeon beforecutting by touching the tip of the device to a pattern drawn out by thesurgeon on the patient's sternum. Upon completion the pre-indicatedpattern is found to make closing the sternum after cardiac thoracicsurgery has completed, much easier to perform and stable.

OTHER EMBODIMENTS

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or exemplary embodiments are only examples, and arenot intended to limit the scope, applicability, or configuration of thedescribed embodiments in any way. Rather, the foregoing detaileddescription will provide those skilled in the art with a convenient roadmap for implementing the exemplary embodiment or exemplary embodiments.It should be understood that various changes can be made in the functionand arrangement of elements without departing from the scope as setforth in the appended claims and the legal equivalents thereof.

1. An articulating drill system comprising: a hand-held portion; a drillportion; at least two actuators for controlling between two andfive-degrees-of-freedom of said drill portion; a navigation system forcontrolling said at least two actuators; and at least three markersattached to, or incorporated with said drill portion to permit thenavigation system to track the drill portion independent of the positionand orientation of the hand-held portion.
 2. The system of claim 1wherein the navigation system comprises an optical tracking system incommunication with one or more real-time processing computers.
 3. Thesystem of claim 1 wherein the at least two actuators are housed in thehand-held portion about a user's grip.
 4. The system of claim 3 whereinthe at least two actuators comprise at least two motors assembled withother components that convert rotational motion to a linear motion toadjust a distance and angle of the drill portion relative the hand-heldportion, wherein the linear motion is along a vertical axis that issubstantially parallel to a longitudinal axis of the hand-held portion.5. The system of claim 4 further comprising a tool operated by the drillportion, wherein the tool has a tool axis that remains non-parallel tothe vertical axis of the linear motion while the drill portion iscontrolled in at least two-degrees-of-freedom.
 6. The system of claim 5further comprising a motor housed in the drill portion to rotate to thetool.
 7. The system of claim 6 wherein the tool is configured to drillinto bone.
 8. The system of claim 1 further comprising a frontcontroller and a rear controller in communication with the navigationsystem, wherein the at least two actuators comprise a front actuatorcontrolled by the front controller and a rear actuator controlled by therear controller.
 9. The system of claim 8 further comprising a frontscrew actuated by the front actuator, a rear screw actuated by the rearactuator, a front screw nut assembled to the front screw to translatealong the front screw upon rotational motion of the front screw, and arear screw nut assembled to the rear screw to translate along the rearscrew upon rotational motion of the rear screw.
 10. The system of claim9 further comprising a front linear rod having a first end assembled tothe front screw nut and an opposing end assembled to the drill portion,a rear linear rod having a first end assembled to the rear screw nut andan opposing end assembled to the drill portion, wherein the front linearrod and rear linear rod translate independently upon rotation of eitherthe front screw or the rear screw to control at leasttwo-degrees-of-freedom of the drill portion.
 11. The system of claim 10wherein either the opposing end of the front linear rod or rear linearrod are assembled to the drill portion by way of a hinge mechanism. 12.The system of claim 10 wherein the translation of the front linear rodand second linear rod is along a vertical axis that is substantiallyparallel to a longitudinal axis of the hand-held portion.
 13. The systemof claim 12 further comprising a tool operated by the drill portion,wherein the tool has a tool axis that remains non-parallel to thevertical axis of translation while the drill portion is controlled in atleast two-degrees-of-freedom.
 14. The system of claim 13 furthercomprising a motor housed in the drill portion to rotate the tool. 15.The system of claim 14 wherein the tool is configured to drill intobone.
 16. The system of claim 1 wherein the at least two actuators is nomore than two linear actuators to control the drill portion intwo-degrees-of-freedom.
 17. The system of claim 1 wherein the at leastthree markers are configured on a marker array, wherein the marker arrayis attached to the drill portion.
 18. The system of claim 1 wherein theat least three markers are directly attached or incorporated on thedrill portion.
 19. The system of claim 1 further comprising at least onelight emitting diode (LED) marker attached or incorporated on the drillportion for transmitting data, wherein a microcontroller actuates theLED marker to transmit data to the navigation system.